if you behave kindly towards a bad person, they will be mean; conversely, if you behave spitefully, they will be kind to you

Ellipsis of oignez vilain, il vous poindra ; poignez vilain, il vous oindra.

there's a fine line between... (said of things that are very close to one another, such that one could easily lead to the other)

out of the question! it's out of the question!

(informal) that's partly right, that's part of it, that's kind of the idea, sort of, that's sort of it

(somewhat literary) … ago

Alternative form of il y a de ça

(informal) that's putting it a bit strongly, that's taking it a bit far, that's not quite right

(informal) it takes what it takes; you gotta do what you gotta do; there's no point in skimping

(informal) Said of something that is seemingly endless, never-ending or inexhaustible.